How will IBEX communicate data?
IBEX will complete one orbitThe curved path, usually elliptical, described by a planet, satellite, spaceship, etc., around a celestial body, such as the Sun. every five to eight days, depending upon conditions at launch. Each orbit, there is a period of time when the spacecraft is inside Earth's magnetosphereThe region around a planet where particles from the solar wind are trapped by the planet's magnetic field.. This is an ideal time to communicate with Earth because, being close to the Earth, it does not take a lot of power to send signals back and forth. It uses antennae that are attached to the outside of the spacecraft to send radio signals to receivers on Earth. Due to the rotation of the Earth each day, the IBEX team needs a global network of receivers so that no matter how the satellite and Earth are lined up, there is a receiver available to accept the signal. IBEX has partnered with the Universal Space Network, which is designed to arrange receiving communications from many other missions and satellites. IBEX is never further away from Earth than the Moon, so it takes a second or less for signals to travel between the spacecraft and Earth.
However, IBEX data transfer rates are slow compared with other telescopes due to the nature of the data it collects. IBEX does not need a "high speed" connection, since it only has the opportunity to collect up to a few particles per minute. Communication from the satellite to the ground is 20 times slower than a typical home cable modem (320,000 bits per second,) and from the ground to the satellite only 2,000 bits per second, which is 250 times slower! Once the signal is collected by the receivers on Earth it is carried over the internet to Mission Control Center in Dulles, VA and to the IBEX Science Operation Center in San Antonio, TX.
|
